Chromosome-scale assembly and analysis of Melilotus officinalis genome for SSR development and nodulation genes analysis

Melilotus officinalis is an important legume crop with forage and Chinese medicinal value. The unknown genome of M. officinalis restricted the domestication and utilization of the species and its germplasm resource diversity. A chromosome-scale assembly of the M. officinalis genome was assembled and analysed. The 976.27 Mb of genome was divided into eight chromosomes covering 99.16% of the whole genome. A total of 50022 genes were predicted in the genome. M. officinalis and Melilotus albus shared a common ancestor 0.5-5.65 million years ago (MYA). A genome-wide doubling event occurred 68.93 MYA according to the synonymous nucleotide-substitution values. A total of 552102 tandem repeats were predicted, and 46004 SSR primers of TRs with 10 or more base pairs were developed and designed. The elucidation of the M. officinalis genome provides a compelling model system for studying the genetic, evolutionary and biosynthesis of this legume.